Getting Error Message While Attempting To Update

Awhile back perhaps 2 months or so I attempted to install an update to ver 3.5.1. I got an error message" "The server returned the following unexpected response: Response Code: 403.
I have been using and updating the software on the same lap top using Win XP for most of the year since its release. My last successful update was in Aug 2007, and I have been unable to obtain any further updates.
Any suggestions to download the current updates?